Muffler



P 1932- v I OLDBERG 1,878,424

' mum I Filed Oct. 26. 1931 a smegma .1

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Filed 0ct. 26, 1931 3 Sheets-Sheet 2 L 2 I 4/ M" o e o o 0 :2

4a 1 .7 I INVENTOR.

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Patented Sept. 20, 1932 I UNITED STATES PATENT. OFFICE VIE-GIL OLDIBEBG, OF DETROIT, MICHIGAN, ASSIGNOIB' TO OLDZBEBG MANUFACTURING COMPANY, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN MUFFLER Application filed October 2c, 1981, Serial no. 371,188,

This invention relates to mufllers and more particularly to automobile engine mufliers of the thru type.

Mufllers of the tru type, include an outer shell having heads which are connected by and thru which passes an inner shell, the latter being entirely free of baflles, etc., and being rovided with perforations, between the hea s, leading into the annular space between 1. the shells. Mufilers of this t pe are advan:

tageous' in that they are free f iom back ressure, and if suitable means between the s ells be provided to absorb or neutralize sounds arising within the mufllers, the mufiler is 15' found to be highly eflicient as a means for eliminating no1ses which occur in engine operation.

An object of the invention, therefore, is a mufier of the thru type provided with means so in the annular space between the shells, to neutralize sounds. More particularly, the

invention aims to provide resonators in the space between the shells, as contrasted with mufllers, such as have previously been pro- 26 vided, and which-include sound absorbing media disposed between the shells.

, A still further object is a mufiier of the character above described which is provided with a bafile at its end to prevent flames from 80 passin out of the mufiler.

A still further object is a mufller having transverse diaphragms between the shells, the diaphragms being formed of ribs extending inwardl or outwardly from one or moreof the shel s, as desired. I

Still further objects will readily occur to those skilled in the art upon reference to the following description and the accompanying drawings in which: I

' Fig. 1 is a half longitudinal section of one form of the mufiler. a

Fig. 1a is a similar section showing a slightly modified form.

Fig. 2 is a longitudinal central section showing a still further modified form.

Fi s. 3 and 4 are longitudinal sections showing the type of mufller of Figs. 1 and 2 with theaddition of a resonator.

Fi 4a is a section showing a modification to of Fig. 4. 4 i

Fig. 5 is a section thru Fig. 3 on the line Figs. 6 and 6a are longitudinal sections thruthe mufiler involving some of the features of Figs. 2, 4 and 4a.

Figs. 7 to 10 show further modifications. Referringto the drawings and more particularly to. Figs. 1 and la, it will be seen that the mufiler of this form includes an outer dicated at A pluralityof small, closely spaced perforations 19 in the shell 14afiord' communication between the interior of the.

shell 14 and the several resonating chambers. In Fi 1a a similar'construction is shown exce t t at the diaphragms 16a and 1811 will be 0 conical form towhich reference-will be made later.

It will be seen that the gases from the en gine pass thru the inner shell 14 without are. resonated b the bodies of gas in the resonating chambers R, the fluid bodies within such chambers being separated by the diaphragms 16 and 18. I

In Fig. 2 there is disclosed a mufiler includin an outer shell 20 having heads 21, and a iaphragm 21a the latter and the after head 21 supportingthe tube 14, which is similar in all respects to the tube 14 of Fig. 1. Between the forward head 21 and the diaphragm 21a is a receiving chamber 22 into which the gases pass from the motor, being then led out thru the tube 14 in the fashion indicated in Fig. 1. In this form of mufiler,

the tube 14 is shownas supported by conical diaphragms 18a as in Fig. 1a. This provides obstruction and that sounds within the mufiler resonating chambers R between the diaphragms 18a as in theprevious forms, but a further modification in this figure is shown in providing the diaphragm 21a with openings 2211 thru which a part of the gases pass into the chamber 23 and then back into the tube 14 thru the holes 19, passing on out thru the discharge end of the tube.

.these being connected by the inner tube 34 and the intermediate shell 35. The inner shell 34 is provided with minute perforations 36, opening into the space between the inner parts 34 and 35 which is filled with a sound absorbing media 37, such as steel wool, mineral wood, or loosely packed fiber or the like.

The space between the shells and contains two resonating diaphragms 38 which form resonating chambers R, communicating with the spaces between the heads 31 and 33 thru slots 39 in the outermost portions of the heads 33.

It will be seen that in this form the gases pass from one nipple 32 to the other without interference, there being no baflies in the path of flow of the gases. Certain of the gases, however, pass from the spaces between the heads 31 and 33, thru the slots 39 and into the resonating chambers R, to set up resonating vibrations in these chambers.

In the form shown in Figs. 4 and 4a, the structure is quite similar to that of Figs. 3, except that instead of the media 37, this is replaced with a plurality of chambers 37a produced by the insertion of the diaphragms 37b in Fig. 4 and 370 in Fig. 4a, ence in the diaphragm being that the latter are conical rather than plane.

Figs. 6 and 6a show forms of mufilers which correspond most nearly to that of Fig.

4, but with the modification shown in Fig. 2.

.In this figure, the outer cylinder 20 is, of

course, the outer imperforate wall and the inner cylinder is, of course, the tube 14 with the perforations 19. The resonating chamber R opens out of the chamber B through the openings 220 which are of considerable size. The secondary resonating chambers R are constructed and operate in the same manner as the corresponding chambers inthe previously described forms.

In Fig. 6a there is shown a construction which is similar to that of Fig. 6, except that there is a receiving chamber C for the gases and this chamber communicates with the resonating chamber B through the openings 22d and also communicates with the tube 14 through the chamber 23a through openings 22a and perforations 19, as in Figs. 2.

In Fig. 7 there is shown a mufiler which is very much like those disclosed in the previous figures, except that in the space between the slotted head 41 andthe end head 42 a conical perforated baflle 43 is disposed, and bafile opening towards the exit nipple 44. A bafiie of this character serves the useful purpose of preventing flames which might be present in the mufiler from passing out thru the nipple 44.

In Figs. 8, 9 and 10, there are disclosed mufilers which are very much like the mufiier of Fig. 6a, except thatthe diaphragms in the space between the inner shell and the intermediate shell 51 are formed by rolled annular ribs 52 integral with the inner shell and projecting outwardly therefrom and into engagement with the intermediate shell 51 forming resonating chambers B- similar to those disclosed in Fig. 1. Resonating chambers of a trapezoidal cross section have proven to be very eflicient, much more so than resonatin chambers of the rectangular cross section of Fig. 2.

In Fig. 9 there is disclosed a mufiler which is more or less like the muflier of Fig. 8 except that the partitions between the inner shell and the intermediate shell 61 are.

formed by rolled annular ribs 62 projecting inwardly from the intermediate shell and engaging the wall of the inner shell to form resonating chambers R of trapezoidal cross section.

Fig. 10 discloses a muffler which is also very much like the form of Fig. 8 except that the diaphragm between the inner shell 70 and the intermediate shell 71 comprise annular ribs 7 2 rolled outwardly from the inner shell and annular ribs 7 3 rolled inwardly from the intermediate shell. These ribs enage one another and are secured to one another toform transverse partitions to form resonating chambers R which, as disclosed, have alozenge shaped cross section having all of the advantages of the trapezoidal cross section resonating chambers disclosed in Figs. 7 and 8. r

The simplest form of mufller shown in the drawings, is, of course, that shown in Fig. 1 which provides merely the lateral resonating chambers. However, it has been found that if the diaphra 'ms are formed conical in shape a further efiect in eliminating noise is gained. It seems to be that the exact angle will vary with different conditions but satisfactory results have been obtained through the use of angles ranging from 20 degrees up to degrees with a maximum 'efiiciency near the centralpoint of this range. The inclination of the diaphragm chamber toward or awa. from the -rear end'seems to make little di erence.

It has also been found that if a proportion of the gases are shunted from the receiving chamber and introduced into the outlet tube at a short distance away from the chamher, a further efiect in decreasing noise will be obtained. These effects can, of course,-

obtained without increasing the back pressure of the muffler, which back pressure in the form shown, is practically zero.

Now having described the invention and the preferred embodiment thereof, it is to be understoodthat the said invention is to be limited, not to the specific details herein set forth, but only by the scope of theclaims which follow:

What I claim is:

1. In a mufiler for the exhaust gases of an internal combustion engine, wherein exhaust gases and sound waves travel in the same direction, the combination of an intermediate shell havin apertured end headers, a shell telescoped t erein and providing a thru and unobstructed passage for exhaust gases thru the mufiler from an engine to the atmosphere, the latter shell havin a relatively large portion ofits entire sur-ace covered with a plurality of relatively small, closel spaced, perforations, there being a plura ity of a'nnular, spaced, substantially imperforate diaphra'gms in the annular space between the aforementioned shells to provide a plurality of annular, elongated, sound attenuating chambers in said space, the perforations opening into said chambers, the mufller also having an outer imperforate shell surrounding the aforementioned shells, the outer shell being closed at its ends and also being placed in communication with the interior of the intermediate shell thru large openings there- 1n.

2. In a muflier for the exhaust gases of an internal combustion engine, wherein exhaust sound attenuating chambers in said space, the

' perforations opening into said chambers, the

mufiler also having an outer imperforate shell surrounding the aforementioned shells, the

outer shell being closed at its ends and also being placed in communication with the 1n- I terior of the intermediate shell thru large openings therein. a

3. In a mufller forthe exhaust gases of an internal combustion engine, wherein exhaust gases and sound waves travel in the same direction, the combination ofan intermediate shell having apertured end headers, a shell telescoped therein and providing a thru and unobstructed passage for'exhaust gases thru the mufller from an engine to the atmosphere, the latter shell'having a relatively,v

lar e portion of its entire surface covered wit a plurality of relatively small, closely spaced, perforations, there being, in the annular space between the aforementioned shells, means for attenuatin to a marked degree, sound waves caused y gases coursing thru the innermost shell, the perforations opening into said annular s ace, the mufller a so having an outer imper orate shell surrounding t e aforementioned shells, the outer shell being closed at its ends and also placed in communication with the interior of the intermediate shell thru large openings therein.

In testimony whereof, I sign this specifica- VIRGIL OLDBERG.

tion. a 

